The present invention broadly relates to an apparatus for measuring the arcuate length of arcuate strip articles, and more particularly for measuring the interference or height of shell-type half bearings.
Shell or sleeve-type precision half bearings which are of a generally semi-circular cross section are in widespread use for rotatably supporting journals such as crankshafts and connecting rods in automobile internal combustion engines and the like. Such shell-type bearings are generally of a composite construction comprising a hard metal backing strip such as steel to the inner concave surface of which a thin bearing lining is tenaciously bonded and machine finished to precision tolerances. A typical method of manufacturing such shell-type half bearings through a sequential blanking, stamping, forming, trimming, machining and finishing sequence is described in U.S. Pat. No. 3,206,830 granted Sept. 21, 1965 to the assignee of the present invention, the teachings of which are incorporated herein by reference by way of example.
One of the several important dimensional tolerances that must be maintained within specifications is the interference or height of the shell-type half bearing which most commonly is that distance beyond a certain number of arc degrees, usually 180 degrees, that one parting edge of the bearing projects. A proper interference or height of such precision shell-type half bearings is necessary to assure a proper seating of two assembled half bearings such as in a connecting rod and connecting rod cap forming a press fit upon final assembly.
In accordance with conventional quality control practices, final finished bearings are manually inspected including a manual measurement of the interference or height to assure that they are within specifications. Such manual inspection is not only tedious and time-consuming, but also is costly and labor intensive in consideration of the large volume of such bearings produced in automatic manufacturing machines.
The present invention overcomes many of the problems and disadvantages associated with prior art manual interference measuring techniques by employing an apparatus which is adapted to operate at high speed for measuring each individual bearing transferred from final finishing operations. Further, it provides an accurate reading of the interference or height thereof under measuring conditions that can be maintained substantially constant thereby assuring precision products. The present invention further provides for flexibility and versatility in enabling automatic measurement of shell-type half bearings of different sizes and is readily adaptable to conventional instrumentation for segregating bearings within prescribed specifications from those outside such specifications.